I'm not sure about the formula.
But since 38/2=19
19-2=17
Linda is 17 years old.
a possible formula could be:
L=38/2-2
For problems like this you can move the y's on the bottem up top by fliping the sign of the exponent (in this case 7 to -7) and MULTIPLYING it with EVERYTHING on top, then because of properties of multplication you can add the exponents to combine them into one term (in this case add 3 and -7 to get -4)

If any of this does not make sense let me know and ill try to clarify better